HOME and how to join Forum Open Area General Scott topics Brum head separation answer Reply To: Brum head separation answer

#7579
efr215
Participant

I am wondering just how effective this resistance heating idea might be despite the claim that it has worked previously.

Firstly let us consider the limits in such an exercise; the melting point of aluminium is about 660°C and as we don’t particularly want to melt the aluminium let us establish for arguement an absolute, (and optimistic), upper temperature of 500°C for this operation. The danger is that at these temperatures even modern aluminium is pretty fragile and the technology has moved on a lot since Scott castings were made, some of which are, shall we say, a bit “iffy”? In fairness it ‘aint that long ago that aluminium was a rare and expensive, even precious, metal which is why some medals were once made of it as was the statue of Eros in Piccadilly Circus.

At 500°C a steel stud will increase its diameter by about 0.002” and the aluminium hole by about 0.004”. The axial elongation of the stud will also help loosen the “grip” but it is the difference in expansion that will break the “grab” and that will still be only 0.006”/inch even though the stud overall will elongate by maybe 0.020”

Now that might be enough but there is still the question of the current required, something in excess of a continuous 300A by my estimation, so how many of you have access to a wopping big welder?

Finally there is the amount of preparation that will be needed if there is to be any reasonable expectation of success. Witness the amount of work Roger has described with his previously mentioned successful pressure method. Preparation, like genius, should not be underestimated; it also consists of 90% perspiration! And usually takes at least twice as long as you think it will into the bargain!

On balance I still consider that cutting the studs through the head gasket joint and dealing with them one by one is the safer and overall quicker method.